Kidde KN-COEG-3 Nighthawk AC Plug-in Operated Carbon Monoxide and Explosive Gas Alarm. It provides dual protection against carbon monoxide (CO), natural gas (methane), and propane. The alarm features a digital display that shows the level of CO sensed or indicates "GAS" when explosive gas is present. It includes a 9V battery backup to ensure continuous monitoring during power outages. A peak level memory function allows viewing the highest recorded CO concentration since the last reset.